DENVER -- The next time you go to your doctor’s office, be prepared to pay.

And not just your co-pay.

A growing number of Colorado physicians are asking for more of your money upfront.

People with health insurance have grown accustomed to a paying a small co-pay and getting billed later.

That’s how it always worked for cancer survivor Lori Conway.

“I don’t think the doctors should ask for the money upfront,” she said. “It’s their responsibility to submit those claims to the insurance company.”

But more and more doctors are telling patients to pay up before they walk out.

Gary Biggs paid $15,000 ahead of his recent jaw surgery.

“Obviously, I liked knowing in advance, so I could prepare for it,” said Biggs.

A recent survey of Colorado physicians by NaviNet Inc. showed almost 60 percent have procedures in place to collect payments above and beyond co-pays (such as remaining deductibles ) at the time of the visit.

“If they collect it up front, it eliminates the need for them to try to get it 30, 60, 90, 120 days, and in a lot of cases never,” said Andrew Graham, president of Clinic Service Corporations, Colorado’s largest medical billing company.

He said he discourages doctors from seeking money up-front, but that many are doing it anyway if their insurance companies allow it.

After all, one NaviNet Inc., survey showed more than 60 percent of Colorado doctors who responded have had an increase in uncollected debt.

“If you sit around long enough and don’t get paid long enough, then you’ve got to change your behavior,” said Graham.

Graham recommended talking to your doctor up-front about billing practices.

Also, he said, not all insurance companies allow doctors to charge up-front, so know what your policy says.

With new insurance billing software, most doctors offices are able to determine what you will owe, but in some cases, it’s an estimate.

Graham said if a doctor over charges, he should refund the money as soon as possible.